This invention relates to a method that allows or provides for increased incorporation of whey protein (in the form of xe2x80x9cfunctionally enhancedxe2x80x9d whey protein) in cheese. The method uses high shear mixing and carefully controlled heat treatment to provide the functionally enhanced whey protein. This functionally enhanced whey protein can be incorporated into cheese products to provide stable products having increased levels of whey protein without adversely affecting the organoleptic properties of the resulting cheese products.
Cheese compositions are generally prepared from dairy liquids by processes that include treating the liquid with a coagulating or clotting agent. The coagulating agent may be a curding enzyme, an acid, or a suitable bacterial culture or it may include such a culture. The coagulum or curd that results generally incorporates casein that has been suitably altered by the curding process, fats including natural butter fat, and flavorings arising during the processing (especially when using a bacterial culture as the coagulating agent). The curd is usually separated from the whey. The resulting liquid whey generally contains soluble proteins not affected by the coagulation; such proteins are, of course, not incorporated into the coagulum.
Nevertheless, whey proteins have high nutritive value for humans. In fact, the amino acid composition of such whey proteins is close to an ideal composition profile for human nutrition. Whey proteins are also understood to have superior emulsifying capabilities in comparison with casein. Without wishing to be bound by theory, the incorporation of whey protein is expected to reduce defects such as phase separation during processing, and, in the case of cream cheese, to also provide a smoother creamier product. In addition, such whey proteins provide a low cost dairy product which, if successfully incorporated into cheese products, would significantly increase the overall efficiency and effectiveness of the cheese-making process.
Unfortunately, methods or attempts to incorporate or use whey protein in cheese products have generally been unsuccessful. For example, whey proteins have been concentrated or dried from whey and then recombined with cheese (see, e.g., Kosikowski, Cheese and Fermented Foods, 2nd ed., Edwards Brothers, Inc., Ann Arbor, Mich., 1977, pp. 451-458). The whey proteins recovered from such procedures, however, do not have the appropriate or desired physical and chemical properties required for good or high quality natural cheeses or process cheeses.
An alternative approach has been to coprecipitate whey proteins with casein (see, e.g., U.S. Pat. No. 3,535,304). Again, however, the final product of this process lacks the proper attributes for making good or high quality processed and imitation cheeses. A further attempt to incorporate whey proteins into cheese products has employed ultrafiltration of milk to concentrate all the components, such as the casein, the whey protein, and the butterfat, that do not permeate the ultrafiltration membrane. When such a composition is coagulated by contact with an acid or rennet, a curd is formed. This curd, however, loses considerable quantities of the whey protein when compacted. For example, in U.S. Pat. No. 4,205,090 milk was concentrated to about one-fifth of its original volume. The resulting curd prepared from such concentrate could only be used to provide soft cheeses such as Camembert or Roblechon.
Ernstrom et al. (J. Dairy Science 63:2298-234 (1980)) described a process in which milk was concentrated to about 20 percent of the original volume by ultrafiltration, diafiltration, and evaporation. The resulting composition was inoculated with a cheese starter to ferment the lactose and form a cheese base. This base can be used to replace natural cheese components of process cheese. This process does not, however, employ any renneting or curding step to prepare a cheese curd.
U.S. Pat. No. 5,356,639 discloses a process for the production of a fermented concentrate from various milk products (e.g., whole milk, skim milk, or milk with added milk components); the fermented concentrate was usable to make cheese. The process included the steps of (1) selectively concentrating milk; (2) increasing the ionic strength of the concentrate to maintain the milk in the liquid phase and therefore prevent formation of a coagulum both during and after fermentation; (3) fermenting the concentrate with lactic acid producing bacteria; and (4) removing water from the fermented liquid concentrate. The final product includes substantially all of the whey proteins originally present in the milk.
Banks et al. (Milchwissenschaft 42:212-215 (1987)) disclose that heating milk at temperatures from 95xc2x0 C. to 140xc2x0 C. and then acidifying permits a modest increase in protein content in the cheese upon Cheddar production. The resulting cheese, however, developed a bitter off-flavor in this process. Law et al. (Milchwissenschaft 49:63-37 (1994)) also reported that heat treatment of milk prior to cheddaring results in reduction of proteins in whey and/or in acid filtrates of the milk.
Dybing et al. (J. Dairy Sci. 81:309-317 (1998)) suggested that whey protein could be incorporated into cheese curd by concentrating the milk components, coagulating whey proteins using a variety of agents, and renneting a composition containing the coagulated whey protein and concentrated milk components. Unfortunately, none of the methods were successful in producing whey protein that could be recovered as a cheese product.
Guinee et al. (Int. Dairy Journal 5:543-568 (1995)) reviewed the general state of the art relating to incorporation of whey protein into cheese or cheese products. High-heat treatment of milk impairs rennet coagulation, curd syneresis, curd structure and texture, as well as functional properties such as meltability and stretchability of the resulting cheese. The heat treatment of milk, after being curded to form semi-hard cheeses, does allow production of cheeses having higher whey protein levels. Unfortunately, such cheeses also exhibit higher moisture levels, lower pH values, poorer curd fusion, and lower yield (fracture) values during ripening.
An additional way in which expenses in manufacturing cheeses can be reduced is to minimize the content of components that are costly, and to increase the content of components that are inexpensive. Dairy liquids based on milk, containing casein, are relatively expensive, and their use in cheese manufacture increases the cost of the cheeses that result. Thus it would be advantageous to reduce the content of casein-containing dairy liquids in the manufacture of cheeses. It is found in practice, however, that reducing casein and replacing it with a less functional ingredient such as lactose or fat adversely affects texture and emulsion stability during processing. This disadvantage likewise persists when whey proteins that have not been functionally enhanced by the methods of the present invention, are used in an effort to supplement the lost casein.
As suggested above, in spite of many attempts documented over almost three decades, there remains a need for cheese curd and cheese products with an optimal incorporation of whey protein without significant reduction of organoleptic properties. There also remains a need for a method of producing such cheese curd and/or cheese products which allows for the increased incorporation of whey protein in the cheese curd and/or cheese product and which, at the same time, allows for retaining the organoleptic properties normally associated with high quality cheese curd and/or cheese product. Additionally, there remains for a cheese-making process which provides increased yields and efficiencies by incorporating significant levels of whey protein in the resulting cheese products without significantly modifying the organoleptic properties of the resulting cheese products. There further remains a need to reduce the use of casein-containing dairy liquids in cheese products that maintain pleasing organoleptic qualities and flavor of the product. The present invention responds to these long-felt needs and provides such methods and cheese compositions.
The present invention provides a process for making a stable cheese product supplemented with whey protein, said method comprising the steps of:
(i) preparing a cheese curd;
(ii) preparing a whey protein composition;
(iii) combining the cheese curd and the whey protein composition to form a whey protein-cheese curd blend; and
(iv) subjecting the whey protein-cheese curd blend to high shear and an elevated temperature for a time sufficient to provide a stable cheese product supplemented with whey protein. The heat treatment effectively transforms the whey protein to produce a xe2x80x9cfunctionally enhancedxe2x80x9d whey protein which allows for the formation of a stable cheese product containing the functionally enhanced whey protein. Preferably, the blend is homogenized at a pressure of about 1,000 to about 8,000 psi and treated at a temperature from about 175 to about 215xc2x0 F. for about 2 to about 60 minutes. More preferably, the blend is homogenized at a pressure of about 1,500 to about 6,000 psi and treated at a temperature from about 180 to about 205xc2x0 F. for about 5 to about 45 minutes. Even more preferably, the blend is homogenized at a pressure of about 3,500 to about 5,000 psi and treated at a temperature from about 180 to about 205xc2x0 F. for about 5 to about 30 minutes.
In an alternative process for making a stable cheese product supplemented with whey protein, the steps include:
(i) combining a whey protein composition with a dairy liquid to form a culturable mixture;
(ii) subjecting the mixture to a high shear homogenization and temperature treatment that is effective to functionally enhance the whey protein, such that it is substantially incorporated into the milk fat-casein structure, thereby stabilizing the culturable mixture;
(iii) culturing the stabilized mixture with a culture that provides a particular variety of cheese to form whey and a cheese product characteristic of the particular variety of cheese;
(iv) heating the cultured mixture; and
(v) separating the cheese product from the whey in the heated mixture.
In significant embodiments of this method, the mixture is homogenized in step (ii) at a pressure from about 1,500 to about 3,500 psi. In a more significant embodiment, the homogenization is carried out at a pressure from about 2,000 to about 3,000 psi. The temperature treatment in step (ii) entails heating the mixture to about 180 to about 220xc2x0 F. for about 1 to about 10 minutes. Preferably, the mixture is heated to about 195 to about 205xc2x0 F. for about 4 to about 6 minutes. After the homogenization step, that may include or be combined with an ultrafiltration step, the mixture is subjected to an extended controlled heat treatment. In a preferred embodiment, the cultured mixture is heated in step (iv) to a temperature from about 165 to about 210xc2x0 F. In an additional preferred embodiment,. the cultured mixture is treated in step (iv) at a temperature from about 195 to about 205xc2x0 F. The characteristic cheese product thus obtained stably incorporates the functionally enhanced whey protein. In preferred embodiments of these methods, the cheese curd is a cream cheese curd, and the cheese product is cream cheese.
In important embodiments of both processes, the whey protein composition is selected from the group consisting of dry whey protein concentrate (WPC), liquid whey protein concentrate (WPC), whey protein isolate, liquid or dried sweet whey, liquid or dried acid whey, and mixtures thereof. Dry whey protein is combined at a proportion from at least about 2 percent by weight of the total weight of the blend to at most about 12 percent of the total weight of the blend. Alternatively, liquid whey protein concentrate (WPC) is added at a proportion such that the whey protein concentrate solids contained therein are present at a proportion from at least about 2 percent by weight of the total weight of the blend to at most about 12 percent by weight of the total weight of the blend. Furthermore, whey protein isolate, which contains about twice the concentration of whey protein solids as does whey protein concentrate, can be used in the present invention. Accordingly, about one-half the volume of whey protein isolate can be used, compared to whey protein concentrate. Liquid or dried sweet whey and liquid or dried acid whey can also be used. Mixtures of two or more of these whey protein compositions can also be used if desired.
The invention further provides a stable cheese product that is characteristic of a particular variety of cheese supplemented with whey protein that includes the cheese product and functionally enhanced whey protein. In a preferred embodiment, the cheese product is cream cheese.
The methods and products of the invention further provide for reducing the content of casein-containing dairy liquids in the processes for making cheeses, and in the resulting cheese products. This reduction is attainable since the incorporated functionally enhanced whey protein effectively replaces the functionality of the casein that has been eliminated.